Comparative assessment of the trace-element composition of coals, crude oils, and oil shales

Abstract: A comparative analysis of the amounts of 42 trace elements in coals, crude oils, and oil and black shales was performed. The degree of concentration of trace elements by caustobioliths and their ashes relative to their abundance in argillaceous rocks and the Earth's crust was calculated. Typomorphic trace elements were distinguished, of which many turned out to be common for the different kinds of caustobioliths in question. The trace elements were classified according to their concentration factors in different caustobioliths. The ash of crude oils is enriched in trace elements (Cs, V, Mo, Cu, Ag, Au, Zn, Hg, Se, Cr, Co, Ni, U) to the greatest extent (concentration factor above 3.5) and that of oil shales is enriched to the least extent (Re, Cs, Hg, Se). The ratios between typomorphic trace elements in general strongly differ from those in the Earth's crust and argillaceous rocks and are not identical in different caustobioliths. Quantitative parameters that make it possible to calculate a change in these ratios on passing from one caustobiolith type to another were proposed and the relative trace-element affinity of different caustobioliths was estimated.